1. Field of the Invention
The invention relates to a bar closure for installation in the fillet gap of sheet metal cabinet doors.
2. Prior Art
Bar closures consisting of flat strip material, for installation in the fillet gap of sheet metal cabinet doors which are supported longitudinally displaceable on the door panel outside of the lock, are known from the European patent number 0176890. Sheet metal cabinets with leaf shaped doors have limited stability. These doors have high closing requirements because they are provided with an angle bent edge forming the fillet gap. Such cabinet doors can potentially warp, twist and sometimes are subjected to particularly high stresses. If these are doors of electrical switch cabinets containing high-voltage switches, arcing can occur within the cabinet which leads to the explosive release of arc gases. This subjects the door to high pressure.
Therefore, it is important to form bar closures for leaf shaped sheet metal cabinets in a way that the door is securely connected to the body of the cabinet so that the door can also absorb the described loads. This means in the case of tall switch cabinets locking at three points of the door the region of the closure as well as at the upper and at the lower end as is the case with most bar closures, the locking elements formed by the lock itself as well as by the bar ends is sufficient. If additional locking points are provided, they must be arranged in the central region of the bar, which creates diverse problems. For one, it is difficult to make the arrangement in such a way that the bars remain axisymmetrical. Such axial symmetry, however, has the advantage that it ensures exchangability of the bars, which is extremely important for cost-effective production and simple installation. Another problem is that some locking means place a uni-lateral load on the flat strip bars causing tilting which is detrimental to their operation. Changes in the known bar closure structures are only possible to a limited extent should changes become necessary due to moving a cabinet, changing the closing conditions or the like.
Problems of warping are particularly grave for bars consisting of flat strip material. On the other hand, such flat strip bars are important for switch cabinets with sheet metal doors having a fillet gap because they utilize the otherwise dead space in the bent region and do not occupy utilizable space within the switch cabinet. In addition, this arrangement has the advantage that the closure is outside the switch cabinet sealing area. Therefore, apertures required for the bar closure do not need to be included under the sealing measures. This saves sealing material, simplifies the installation, and decreases the danger of sealing breakdown that occurs under some operating applications.